It is no secret that Barack Obama does not have much use for the United States Constitution. It is a governing plan for a free, self-determining people. Hence, it is littered with roadblocks against schemes to rule the people against their will. When it comes to our imperious president’s scheme to enable our enemy, Iran, to become a nuclear-weapons power — a scheme that falls somewhere between delusional and despicable, depending on your sense of Obama’s good faith — the salient barrier is that only Congress can make real law.

Most lawmakers think it would be a catastrophe to forge a clear path to the world’s most destructive weapons for the world’s worst regime — a regime that brays “Death to America” as its motto; that has killed thousands of Americans since 1979; that remains the world’s leading state sponsor of jihadist terrorism; that pledges to wipe our ally Israel off the map; and that just three weeks ago, in the midst of negotiations with Obama, conducted a drill in which its armed forces fired ballistic missiles at a replica U.S. aircraft carrier.

This week, 47 perspicuous Republican senators suspected that the subject of congressional power just might have gotten short shrift in Team Obama’s negotiations with the mullahs. So they penned a letter on the subject to the regime in Tehran. The effort was led by Senator Tom Cotton (R., Ark.), who, after Harvard Law School, passed up community organizing for the life of a Bronze Star–awarded combat commander. As one might imagine, Cotton and Obama don’t see this Iran thing quite the same way.

There followed, as night does day, risible howls from top Democrats and their media that these 47 patriots were “traitors” for undermining the president’s empowerment of our enemies. Evidently, writing the letter was not as noble as, say, Ted Kennedy’scanoodling with the Soviets, Nancy Pelosi’s dalliance with Assad, the Democratic party’s Bush-deranged jihad against the war in Iraq, or Senator Barack Obama’s own back-channel outreach to Iran during the 2008 campaign. Gone, like a deleted e-mail, were the good old days when dissent was patriotic.

Yet, as John Yoo observes, the Cotton letter was more akin to mailing Ayatollah Khamenei a copy of the Constitution. The senators explained that our Constitution requires congressional assent for international agreements to be legally binding. Thus, any “executive agreement” on nukes that they manage to strike with the appeaser-in-chief is unenforceable and likely to be revoked when he leaves office in 22 months.

For Obama and other global-governance grandees, this is quaint thinking, elevating outmoded notions like national interest over “sustainable” international “stability” — like the way Hitler stabilized the Sudetenland. These “international community” devotees see the Tea Party as the rogue and the mullahs as rational actors.

So, you see, lasting peace — like they have, for example, in Ukraine — is achieved when the world’s sole superpower exhibits endless restraint and forfeits some sovereignty to the United Nations Security Council, where the enlightened altruists from Moscow, Beijing, and Brussels will figure out what’s best for Senator Cotton’s constituents in Arkansas. This will set a luminous example of refinement that Iran will find irresistible when it grows up ten years from now — the time when Obama, who came to office promising the mullahs would not be permitted to acquire nuclear weapons, would have Iran stamped with the international community seal of approval as a nuclear-weapons state.

Down here on Planet Earth, though, most Americans think this is a bad idea. That, along with an injection of grit from the Arkansas freshman, emboldened the normally supine Senate GOP caucus to read Tehran in on the constitutional fact that the president is powerless to bind the United States unless the people’s representatives cement the arrangement.

Obama, naturally, reacted with his trusty weapon against opposition, demagoguery: hilariously suggesting that while the Alinskyite-in-chief had our country’s best interests at heart, the American war hero and his 46 allies were in league with Iran’s “hardliners.” (Yes, having found Muslim Brotherhood secularists, al-Qaeda moderates, and Hezbollah moderates, rest assured that Obama is courting only the evolved ayatollahs.) When that went about as you’d expect, the administration shifted to a strategy with which it is equally comfortable, lying.

Obama’s minions claimed that, of course, the president understands that any agreement he makes with Iran would merely be his “political commitment,” not “legally binding” on the nation. It’s just that Obama figures it would be nice to have the Security Council “endorse” the deal in a resolution because, well, that would “encourage its full implementation.” Uh-huh.

Inconveniently, the administration’s negotiating counterpart is the chattiest of academics, Iranian foreign minister Mohammad Javad Zarif. Afflicted by the Western-educated Islamist’s incorrigible need to prove he’s the smartest kid in the class — especially a class full of American politicians — Zarif let the cat out of the bag. The senators, he smarmed, “may not fully understand . . . international law.”

According to Zarif, the deal under negotiation “will not be a bilateral agreement between Iran and the U.S., but rather one that will be concluded with the participation of five other countries, including all permanent members of the Security Council, and will also be endorsed by a Security Council resolution.” He hoped it would “enrich the knowledge” of the 47 senators to learn that “according to international law, Congress may not modify the terms of the agreement.” To do so would be “a material breach of U.S. obligations,” rendering America a global outlaw.

This, mind you, from the lead representative of a terrorist regime that is currently, and brazenly, in violation of Security Council resolutions that prohibit its enrichment of uranium.

Clearly, Obama and the mullahs figure they can run the following stunt: We do not need another treaty approved by Congress because the United States has already ratified the U.N. charter and thus agreed to honor Security Council resolutions. We do not need new statutes because the Congress, in enacting Iran-sanctions legislation, explicitly gave the president the power to waive those sanctions. All we need is to have the Security Council issue a resolution that codifies Congress’s existing sanctions laws with Obama’s waiver. Other countries involved in the negotiations — including Germany, Russia, and China, which have increasingly lucrative trade with Iran — will then very publicly rely on the completed deal. The U.N. and its army of transnational-progressive bureaucrats and lawyers will deduce from this reliance a level of global consensus that incorporates the agreement into the hocus-pocus corpus of customary law. Maybe they’ll even get Justice Ginsburg to cite it glowingly in a Supreme Court ruling. Voila, we have a binding agreement — without any congressional input — that the United States is powerless to alter under international law.

Well, it makes for good theater . . . because that is what international law is. It is a game more of lawyers than of thrones. In essence, it is politics masquerading as a system governed by rules rather than power, as if hanging a sign that says “law” on that system makes it so.

At most, international law creates understandings between and among states. Those understandings, however, are only relevant as diplomatic debating points. When, in defiance of international law, Obama decides to overthrow the Qaddafi regime, Clinton decides to bomb Kosovo, or the ayatollahs decide to enrich uranium, the debating points end up not counting for much.

Even when international understandings are validly created by treaty (which requires approval by two-thirds of the Senate), they are not “self-executing,” as the legal lexicon puts it — meaning they are not judicially enforceable and carry no domestic weight. Whether bilateral or multilateral, treaties do not supersede existing federal law unless implemented by new congressional statutes. And they are powerless to amend the Constitution.

The Supreme Court reaffirmed these principles in its 2008 Medellin decision (a case I described here, leading to a ruling Ed Whelan outlined here). The justices held that the president cannot usurp the constitutional authority of other government components under the guise of his power to conduct foreign affairs. Moreover, even a properly ratified treaty can be converted into domestic law only by congressional lawmaking, not by unilateral presidential action.

Obama, therefore, has no power to impose an international agreement by fiat — he has to come to Congress. He can make whatever deal he wants to make with Iran, but the Constitution still gives Congress exclusive authority over foreign commerce. Lawmakers can enact sanctions legislation that does not permit a presidential waiver. Obama would not sign it, but the next president will — especially if the Republicans raise it into a major 2016 campaign issue.

Will the Security Council howl? Sure . . . but so what? It has been said that Senator Cotton should have CC’d the Obama administration on his letter since it, too, seems unfamiliar with the Constitution’s division of authority. A less useless exercise might have been to CC the five other countries involved in the talks (the remaining Security Council members, plus Germany). Even better, as I argued earlier this week, would be a sense-of-the-Senate resolution: Any nation that relies on an executive agreement that is not approved by the United States Congress under the procedures outlined in the Constitution does so at its peril because this agreement is likely to lapse as early as January 20, 2017. International law is a game that two can play, and there is no point in allowing Germany, Russia, and China to pretend that they relied in good faith on Obama’s word being America’s word.

It is otherworldly to find an American administration conspiring against the Constitution and the Congress in cahoots with a terror-sponsoring enemy regime, with which we do not even have formal diplomatic relations, in order to pave the enemy’s way to nuclear weapons, of all things. Nevertheless, Republicans and all Americans who want to preserve our constitutional order, must stop telling themselves that we have

hit a bottom beneath which Obama will not go. This week, 47 senators seemed ready, finally, to fight back.

It’s a start.

— Andrew C. McCarthy is a policy fellow at the National Review Institute. His latest book is Faithless Execution: Building the Political Case for Obama’s Impeachment.